The latest in human evolution.

[generalbetrayus]

[dickthegrouch]

1. *Rump and the GOP have already taken us back at least three steps

And no bombing required (at least within the US).

[rampartd]

2. what i learned today. chromosomes: humans 23 pair

chimps bonobos gorillas have 24 pair.

copilot went on with some kid of explanation that oe readig did not exactly inform. leaving it here if you don't mind.

Primate Chromosomes: Structure, Counts, and Evolution
Primate chromosomes vary in number and structure, reflecting both conserved features and lineage-specific evolutionary changes.

Chromosome counts in primates
Humans have 46 chromosomes (22 autosomes + 1 sex pair: XX in females, XY in males) biologyinsights.com.

Great apes (chimpanzees, bonobos, gorillas, orangutans) have 48 chromosomes each biologyinsights.com.

Gibbons (family Hylobatidae) have fewer, ranging from 38 to 62 chromosomes depending on species biologyinsights.com.

Old World monkeys (e.g., macaques, baboons) typically have 42–72 chromosomes.

New World monkeys (e.g., marmosets, capuchins) range from 28 to 62 chromosomes.

Prosimians (lemurs, lorises) show wide variation, often with high numbers due to multiple small chromosomes biologyinsights.com.

Evolutionary rearrangements
Differences in chromosome counts among primates are mainly due to fusions, fissions, inversions, and translocations.
A key example is human chromosome 2, which formed from the fusion of two separate chromosomes still present in chimpanzees, gorillas, and orangutans biologyinsights.com. This fusion reduced the total count in the human lineage by two compared to other great apes.

Recent genomic advances
In 2024, NIH-funded researchers published the first complete chromosome sequences for non-human primates, including chimpanzee, bonobo, gorilla, Bornean and Sumatran orangutan, and siamang gibbon National Institutes of Health (NIH)+1.

They found 62–66% of X chromosomes and 75–82% of Y chromosomes are repetitive DNA, making them harder to sequence National Institutes of Health (NIH).

Only 14–27% of ape Y chromosomes align with the human Y, indicating rapid evolution National Institutes of Health (NIH).

Over 90% of ape X chromosomes align with the human X, showing remarkable stability over millions of years National Institutes of Health (NIH).

The study revealed previously unstudied regions in great ape genomes, including species-specific satellite sequences Neuroscience News.

Why it matters
Comparing primate chromosome sequences helps trace human evolution, understand sexual development and fertility, and identify regions under strong evolutionary pressure. The variation in Y chromosome sequences, in particular, may relate to reproductive biology and genetic diversity Neuroscience News.

In summary, primate chromosomes are a mix of conserved structures (like the X chromosome) and rapidly changing elements (like the Y chromosome), shaped by millions of years of evolution and providing key insights into human ancestry.



ai doesn't know that 48 is not greater than 38-62?

A key example is human chromosome 2, which formed from the fusion of two separate chromosomes still present in chimpanzees, gorillas, and orangutans biologyinsights.com. This fusion reduced the total count in the human lineage by two compared to other great apes.

this means that of 24 pairs of chromosomes 1 chromosome fused with another
math : 22 pairs remain, along with the new fused chromosome and the former pairs of the 2 fused chromosomes.

there must be something else going on?

[Aussie105]

3. DNA has a mind of it's own.

Drosophila melanogaster (fruit fly) has 8 chromosomes while some plants have hundreds.

Ophioglossum reticulatum, the adder’s-tongue fern, holds the record with up to 1,440 chromosomes.

In short, that number is irrelevant.

On the other hand . . . missing some human chromosomes or having 3 copies instead of two for some combinations on mating can be biologically disastrous.
In utero death or trisomy 21, for instance.

"Numerical Abnormalities

Numerical abnormalities occur when there is a change in the number of chromosomes. This can involve monosomy, where a chromosome is missing, or trisomy, where an extra chromosome is present.

Trisomy 21 (Down syndrome): Individuals have three copies of chromosome 21, leading to intellectual disability, characteristic facial features, and hypotonia in infancy.

Trisomy 18 (Edwards syndrome): Caused by an extra chromosome 18, resulting in severe intellectual disability, clenched hands, and rocker-bottom feet.

Trisomy 13 (Patau syndrome): Extra chromosome 13 causes intellectual disability, cleft lip/palate, polydactyly, and forebrain malformations.

Monosomy X (Turner syndrome): Females with only one X chromosome often have short stature and infertility. "